If the ethnically mixed and oil-rich Iraqi province of Kirkuk is a bomb waiting to explode, then the divided province of Ninewa, 100 kilometres to the northwest, may be the fuse.
The province is home to Mosul, Iraq's third-largest city, and a capital of Arab culture. While Kirkuk may be the Kurds' Jerusalem, it is Mosul that is the heartland for Sunni Arabs.
It is said that more Iraqi army officers and more members of the Baath Party hierarchy came from Mosul than from any other place in Iraq.
And while there are large numbers of predominantly Kurdish villages in the countryside north of Mosul, no more than a third of the capital's residents are Kurds.
Imagine the consternation then, on April 11, 2003, when Kurdish peshmerga fighters overran the great Arab city after the surrender to U.S. forces by Iraq's Mosul-based 5th Army Corps.
Resistance to the new reality was immediate as Arabs resented the presence of both American and Kurdish elements running their city and patrolling their province.
Most of Ninewa's Arab population boycotted a provincial election in 2005 and a Kurdish majority government resulted.
Saadi Pira, a Kurd,and now senior adviser to Iraqi President Jalal Talabani, ran the 2005 election in Mosul. "We knew we weren't the majority. We won three-quarters of the seats, even though we only had a third of the population." he said. "So we appointed an Arab as governor, and spread around a lot of the key positions."
That may be so, but the next four years also provided an opportunity for Kurdish administrators to redress some of the ethnic practices of Saddam Hussein's time when Kurds were often forced to leave the province and Arabs moved in.
During all this time, radical Sunni groups, including al-Qaeda in Iraq, grew in strength and went on the offensive. Terrorist acts against the Kurdish administrators were met with harsh responses.
Khasro Goran was the Kurdish deputy governor but, in reality, was the strongman during those years.
"I am not an executioner, as Arabs claim," he told the International Crisis Group earlier this year. "It is all too easy to blame us for the disorder and violence ... while absolving the terrorists. We had to take matters into our hands because Arab leadership was wholly lacking."
The outcome of all this Arab-Kurd conflict was twofold.
First, Kurdish forces pulled back to the east bank of the Tigris River that runs through Mosul, leaving the insurgents for the Iraqi and U.S. forces to deal with.
Then, in January this year, the province's Arab majority returned with a vengeance when a hard-line Arab party, al-Habdaa, running on an anti-Kurdish platform, convincingly won election.
This time, there was no talk of power sharing, despite the widely practised concept of muhasasa, in which positions are distributed in a way that reflects each party's electoral vote. Governor Atheel Najayfi declared there was too much to redress; he would govern as a majority.
Kurds have insisted on their share of administrative positions and are boycotting the government until they get it. They forcibly control some 16 of the province's 31 subdistricts and will have no part of the administration as constituted.
As a result, when Mr. Najayfi recently tried to visit one of the subdistricts, he and his motorcade of heavily armed four-by-fours were turned away by Kurdish peshmerga troops with shoot-to-kill orders.
National and regional leaders now are getting into the act.
In Baghdad, Shia Prime Minister Nouri al-Maliki, perhaps preparing to run on an anti-Kurd platform of his own in January's election, has repeatedly criticized the idea of muhasasa and even questioned the nature of federalism, declaring that a central authority was the most important thing.
An outraged Masoud Barzani, president of the Kurdistan Regional Government, accused the Prime Minister of seeking to restore dictatorship.
High emotions are like sparks in a tinderbox such as Ninewa, where some of the country's most violent Sunni extremists hide out.
Driven there from Anbar province to the south, and enjoying the more-or-less open Syrian border, the extremists have proliferated.
Just two weeks ago during Friday prayers, a gunman in a Ninewa mosque shot dead the imam and 14 others in the congregation before blowing himself up. The imam, it turns out, was a member of the moderate Iraqi Islamic Party, a group that had not joined other Arabs in the 2005 election boycott and had worked with the Kurds. Assassination, it seems, was the price this man paid.
More than a share in the province's administration, Kurds also contend those Ninewa districts with a majority Kurdish population, and which their forces occupied in 2003, belong in the Kurdistan Regional Government, a special region within a federal Iraq.
For his part, Mr. Najayfi says there are no such disputed territories to be claimed. "In 1991 [during the uprising against the Saddam Hussein regime]the Kurds took over all areas inhabited by their people," he said. "The Green Line [that marked their enclave]is the border they deserve."
"Najayfi would like his entire province without any Kurds," Mr. Pira, the Kurdish adviser, said. "He's speaking the language of Goebbels."
But behind the bravado and politicking, the Kurds may be angling for a deal.
"Kirkuk is a pressing issue for Kurdish politicians of both parties," a Kurdish MP told the ICG in a report issued Sept. 28. "It has more far-reaching results than demands on the other disputed territories. We rather exaggerate the latter so as to gain leverage for negotiations on Kirkuk."